Heating instrument



Dec. 7, 1948.

Filed Now. 23, 1945 v. v. VARNUM 2,455,453

HEATING INSTRUMENT 2 She'ets-Sheet l Inventor Vc'czaf V Varrzum By QM (am pawn 3M5):

Patented Dec. 7, 1948 UNITED STATES PATENT OFFICE HEATING INSTRUMENT Victor V. Varnum, Tama, Iowa Application November 23, 1945, Serial No. 630,324

2 Claims.

This invention relates to a heating instrument and has for its primary object to reestablish communication through a tubular member of small diameter after the latter has become plugged with a fusable substance such as rubber.

In the manufacture and repair of innertubes such as are used on motor vehicles and particularly when vulcanizing the valve stem into the tube the plastic rubber will flow into the stem so as to seal it and prevent the introduction of air into the tube or the passage of air from the interior thereof. When such conditions obtain it becomes necessary to break the seal through the valve stem and to this end it has been a matter of common practice to heat a short length of Wire to incandescence and to introduce it into the valve stem to melt the rubber which is closing the opening therethrough. Due to the rapid dissipation of the heat from a wire when thus used it is frequently necessary to re-heat the wire several times before completing the opening of the passage in the valve stem with the result of great lossof time. I

Another object of this invention is to facilitate the opening of thepassage through a sealed valve stem and effect economies in so doing.

The above and other objects may be attained by employing this invention which embodies among its features an instrument for burning rubber out of the valve stem which comprises a pair of tubular members of flexible heat resistant nonconducting material such as fibre glass, one of which contains a conductor through its bore while the other contains a coextensive conductor, a filament bridging the ends of the conductors beyond the termini of the tubular members, a handle at the opposite ends of the tubular members and means to supply electrical energy to the conductors to cause the filament to be heated to incandescence.

In the drawings:

Figure 1 is a perspective view of a complete unit for use in clearing a sealed valve stem.

Figure 2 is a diagrammatic view of the electrical connections employed.

Figure 3 is a vertical sectional view through the instrument by which the actual burnin is accomplished.

Figure 4 is a transverse sectional view taken substantially on the line 44 of Figure 3.

Figure 5 is an enlarged fragmentary sectional view through a modified form of burning device.

Referring to the drawings in detail, my improved burning instrument designated generally III comprises a shaft designated generally II which is formed from a tubular core member l2 of flexible, heat resistant, non-conducting material such as fibre glass which has been braded into such tubular form in the customary manner. This core is surrounded by a casing [3 of slightly larger internal diameter than the external diameter of the core I 2 which like the core [2 is formed from a flexible, heat resistant, non-conducting material such as braded fibre glass. The core l2 and the casing l3 are substantially co-extensive in length and extending through the core [2 is a conductor l4 while a similarconductor 15 extends through the casing between the exterior of the core and the interior of the casing so as to be held in spaced insulated relation to the conductor M. The lower end of each conductor extends beyond the ends of the core [2 and the casing l3 and are bent back upon themselves as at [6 and soldered or otherwise permanently connected to the lead wires or conductors ll of a cable l8. A handle l9 provided with a longitudinal bore 20 surrounds a portion of the conductor l 8 adjacent the ends of the core l2 and casing I 3 and this handle is provided with a suitable attaching bushing 2| into which the one end of the shaft H is fitted. The junctions of the conductors and lead wires I! are preferably incompassed within a ceramic enclosure 22 and the bore 20 is packed with a suitable cementitious material 23 which will serve to hold the parts assembled.

Arranged within the upper end of the casing l3 and in abutting relation to the upper end of the core I2 is a ceramic disc 24 having spaced openings through which the upper ends of the conductors l4 and I5 extend. A filament 25 bridges the upper ends of the conductors I4 and I5 and is welded or otherwise attached as at 26 to the ends of the conductors. As illustrated this filament 25 is arranged in an elongated loop so that its opposite legs do not extend beyond the circumferential confines of the casing l3, it being understood of course that the external diameter of the entire shaft H is such as readily to enter the interior of a valve stem.

In the modification illustrated in Figure 5 the filament 25 is preferably embedded in a support 21 of a suitable ceramic material, it being understood that the filament is placed close enough to the surface so that the ceramic material will become heated through conductivity and radiation to effect the desired operation. A suitable thimble 28 encases the exterior of the ceramic material and is clamped or otherwise fastened to the exterior of the casing 13 at the junction of the casing and the bushing or disc 24. It

3 will thus be seen that the filament will be reinforced and support-ed in proper position at all times.

In order to afford a suitable power supply for heating the filament the end of the cable l8 opposite that entering the handle l9 enters a suitable housing 29 containing a transformer 30 and the terminals of the conductors or lead wires I1 are connected to opposite terminals of the secondary 3! of the transformer while the primary 32 is connectedthrough a switch 33 to the conductors 34 of a suitable cable 35 provided with the customary contact plug 36 by means of which communication of the transformer with a'suitable power line may be effected. The switch 33 is provided with a lever 31 which extends'outwardly through a slot 38 in the casing129;and-

carries at its outer end a hook 39 for engagement with a bracket 40 which may be attached tothe handle 19 so that when the instrument i0 is hung? on the hook 35 the power to tl'ie"trans':-' former 3G will' be interrupted and When'=th'e-in st-r'ument'is removedfrom the hook for use thefio'w-"of current through the transformer 'willan: tomatically be restored. A suitable spring clip 44- inay beattach'edto the casing 29 in such a position that when the instrument IE3 is onthe hook; the legs of the 011 541 will engage the handle A protecting thimble 42 may be slipped oVer'the' end of the" l9' to hold the device in: place.

former 30 thus exciting the secondary 3i andinducing a flow of current through theleads ll,

conductors l4 and l5to the filament '25 'which v The in' strument may then be inserted into a sealed will become heated to incandescence.

valve'stem so-as to--melt out "the"rubberaniiwhen the operation has been complet-edthe' instrument is restored to the hook 39 thus shutting off further supply of power tothe"transformer'3ilf Whil'in the foregoing there-has been shown andfdescrib'edthe preferred embodiment-of this invention it is to be understood" that minor' changes'in the details'of construction',combi' nation and arrangement of parts may be resorted to' without departing from thespiritand scope of "the invention as claimed.

What I claim is:

1. An instrument for burning rubber out of a valve stem which includes, a shaft comprising a tubular core of flexible, heat-resistant, non-conducting material, a conductor enclosed by and extending throughout the length of the core, a tubular casing of flexible, heat-resistant non conducting material coextensive with and enclosing said core, a conductor coextensive with the first mentionedconductor between the exterior of the core and the interior of thecasin'g, a heat generating filament bridging the conductors at one end of the shaft, a handle at the opposite end of the shaft and means to supply electrical energy to the conductors to heat the filament to" incandescence, and a body of ceramic material reinforcing said filament.

2. An instrument for burning rubber out of a valve stem which includes, a shaft comprising a tubular core of flexible, heat-resistant, nonconducting material,- a conductor enclosed; by and" extending throughout the length of the "core; a tubular casing officxible,- heat-resistant non conducting material coextensive withandenclosing said -core,"-a conductorcoext'ensive with the first'mentioned conductor between the exterior of' the core'ano"; the interior of the casing, a-heat generating filament bridging the conductors at one end of the shaft, a handle at the opposite end of the shaft and means 'tosupply": electrical energy "to the conductorst'o heat'the filameni; to

incandescence; and a body of ceramicmaterial reinforcing said filament, and a protective" cap enclosing said ceramic material.

VICTOR V. VARNUM;

REFERENCES CITED The following referencesare 'of" recordin the file'of this patent:

UNITED STATES PATENTS Number Name Da e-'- 095929 Carter et al Apple; 1893 77%,624 Waters et a1 Nov."8,"19l) i 2,050,904 Trice" Aug; 11';- 1936 2,411,549 Lindberg Nov; 26; 1946* OTHER REFERENCES? B'etz 'company'catalog of 1927, page 10$} 

